[0001] The present invention relates to pyrazolone compounds, to methods for their preparation,
to compositions containing them, and to methods and use for clinical treatment of
medical conditions which may benefit from immunomodulation, e.g. rheumatoid arthritis,
multiple sclerosis, diabetes, asthma, transplantation, systemic lupus erythematosis
and psoriasis. More particularly the present invention relates to pyrazolone compounds,
which are CD80 antagonists capable of inhibiting the interactions between CD80 and
CD28.
Background to the Invention
[0002] The immune system possesses the ability to control the homeostasis between the activation
and inactivation of lymphocytes through various regulatory mechanisms during and after
an immune response. Among these are mechanisms that specifically inhibit and/or turn
off an immune response. Thus, when an antigen is presented by MHC molecules to the
T-cell receptor, the T-cells become properly activated only in the presence of additional
co-stimulatory signals. In the absence of these accessory signals there is no lymphocyte
activation and either a state of functional inactivation termed anergy or tolerance
is induced, or the T-cell is specifically deleted by apoptosis.
[0003] One such co-stimulatory signal involves interaction of CD80 on specialised antigen-presenting
cells with CD28 on T-cells, and this signal has been demonstrated to be essential
for full T-cell activation. (
Lenschow et al. (1996) Annu. Rev. Immunol., 14, 233-258). It would therefore be desirable to provide compounds which inhibit this CD80/CD28
interaction.
[0004] WO 03/004495 A1 discloses 3-oxo-3,5-dihydro-pyrazolo[4,3-c]quinolin-derivatives as immunomodulating
heterocyclic compounds, a pharmaceutical composition comprising said compound, a method
and use of said compound for clinical treatment of medical conditions which may benefit
from immunododulation. More particularly, this document relates to novel heterocyclic
compounds, which are CD80 antagonists capable of inhibiting the interaction between
CD80 and CD28. Accordingly, this document does neither mention nor suggest the pyrazolone
compounds of the present invention which are CD80 antagonists capable of inhibiting
the interactions between CD80 and CD28.
[0005] US 5,061,705 discloses diarylsubstituted five-membered or six-membered heterocyclic compounds,
processes for their preparation and their use of the prophylaxis and treatment of
disorders. This document neither mentions nor suggests the immunomodulating pyrazolone
compounds of the present invention. In addition, this document does not mention immunomodulation
at all, and moreover, this document is also completely silent with respect to any
inhibition of CD80-CD28 interaction.
[0006] In
Farmaco, Edizione Scientifica., vol. 39, no. 4, 1984, 371-378 Picciola G. et al. disclose the synthesis and pharmacological study of some derivatives
of 2,4-dihydro-3H-pyrazol-3-one in which the compound [2-(4-carboxymethylphenyl)-4-phenyl-5-methyl-2,4-dihydropyrazol-3-one
proved to have antipyretic activity equal to that of ibuprofen and aminopyrine. Accordingly,
the document does not mention the specific immunodulating pyrazolones of the present
invention.
[0007] Likewise,
EP 0269030 A2 which discloses pyrazolone derivatives having inhibitory activity and their pharmaceutically
acceptable salts does neither mention nor suggest the CD80 antagonists of the present
invention. Moreover, the compounds of this document aim at the inhibition of completely
different diseases as is the case for the claimed CD80 antagonists.
[0009] In
Tetrahedron Letters 44 (2003), pages 8063-8067 Jang-Woon Byun et al. describe the preparation of solid-phase active esters from a new pyrazolone
linker resin and in this context they mention the pyrazolone linker 1-(4-carboxyphenyl)-3-(4-nitrophenyl)-2-pyrazolin-5-one
which differs with regard to its structure from the CD80 inhibitors of the present
invention.
[0010] Likewise, the urea and thiourea of 1-(4-aminophenyl)-3-phenyl-5-pyrazolone described
in
GB 629 412 A differ in their structure from the particular compounds of the present invention
and moreover, do not have the desired activity as CD80 inhibitors.
[0011] Also the pyrazolone compounds mentioned in
US 3,576,637 do not have the desired structure of the claimed compounds of the present invention.
In addition, this document discloses a lith-type emulsion which has improved contrast
and halftone dot quality. Moreover, since this documents mentions that a pyrazolone
compound is incorporated with an alkylene oxide in a silver halide emulsion it relates
to a completely different field than the compounds of the present invention.
[0012] Likewise,
EP 0255892 A2 which discloses pyrazolone derivatives as special white coupler for use in a recording
material which contains, on a light-reflecting base, at least three silver halide
emulsion layers, arranged thereon, of different spectral sensitivity and associated
colour couplers, a special 2-equivalent yellow coupler and a special white coupler
being associated with the blue-sensitive silver halide emulsion layer relates to a
completely different field.
Detailed Description of the Invention
[0014] The present invention contemplates a compound of formula (IA) or (IB) or a pharmaceutically
or veterinarily acceptable salt, hydrate or solvate thereof:

wherein
Ar represents an optionally substituted monocyclic or bicyclic aromatic or heteroaromatic
group having from 5 to 10 ring atoms,
R
1 and R
2 independently represent H, or C
1-C
6 alkyl;
R
3 represents H; F; Cl; Br; -NO
2; -CN; C
1-C
6 alkyl optionally substituted by F or Cl; or C
1-C
6 alkoxy optionally substituted by F;
R
4 represents a carboxylic acid group (-COOH) or an ester thereof, or -C(=O)NR
6R
7, -NR
7C(=O)R
6, -NR
7C(=O)OR
6, -NHC(=O)NR
7R
6 or-NHC(=S)NR
7R
6 wherein
R
6 represents H, or a radical of formula -(Alk)
m-Q wherein
m is 0 or 1
Alk is an optionally substituted divalent straight or branched C
1-C
12 alkylene, or C
2-C
12 alkenylene, or C
2-C
12 alkynylene radical or a divalent C
3-C
12 carbocyclic radical, any of which radicals may be interrupted by one or more -O-,
-S- or -N(R
8)- radicals wherein R
8 represents H or C
1-C
4 alkyl, C
3-C
4 alkenyl, C
3-C
4 alkynyl, or C
3-C
6 cycloalkyl, and
Q represents H; -CF
3; -OH; -SH; -NR
8R
8 wherein each R
8 may be the same or different, or form a ring when taken together with the nitrogen
to which they are attached; an ester group; or an optionally substituted aryl, aryloxy,
cycloalkyl, cycloalkenyl or heterocyclic group; and
R
7 represents H or C
1-C
6 alkyl; or when taken together with the atom or atoms to which they are attached R
6 and R
7 form a monocyclic heterocyclic ring having 5, 6 or 7 ring atoms; and
X represents a bond or a divalent radical of formula -(Z)
n-(Alk)- or -(Alk)-(Z)
n- wherein Z represents -O-, -S- or -NH-, Alk is as defined in relation to R
6 and n is 0 or 1.
[0015] Compounds (IA) may exist in the form of tautomers (IA
1):

[0016] Hereafter, the compounds (IA) of the invention may be represented and referred to
in either tautomeric form and it is to be understood that any and all tautomeric forms
of structures (IA) and (IB), in particular (IA), may be included in the invention.
[0017] Compounds of general formula (IA) and (IB) are CD80 antagonists. They inhibit the
interaction between CD80 and CD28 and thus the activation of T cells, thereby modulating
the immune response.
[0018] Accordingly the invention also contemplates :
- (i) a compound of formula (IA) or (IB) or a pharmaceutically or veterinarily acceptable
salt thereof for use in the treatment of conditions which benefit from immunomodulation.
- (ii) the use of a compound of formula (IA) or (IB) or a pharmaceutically or veterinarily
acceptable salt thereof in the manufacture of a medicament for the treatment of conditions
which benefit from immunomodulation,.
- (iii) a method of immunomodulation in mammals, including humans, comprising administration
to a mammal in need of such treatment an immunomodulatory effective dose of a compound
of formula (IA) or (IB) or a pharmaceutically or veterinarily acceptable salt thereof.
- (iv) a pharmaceutical or veterinary composition comprising a compound of formula (IA)
or (IB) or a pharmaceutically or veterinarily acceptable salt thereof together with
a pharmaceutically or veterinarily acceptable excipient or carrier.
[0019] Conditions which benefit from immunomodulation include:
Acute disseminated encephalomyelitis
Adrenal insufficiency
Allergic angiitis and granulomatosis
Amylodosis
Ankylosing spondylitis
Asthma
Autoimmune Addison's disease
Autoimmune alopecia
Autoimmune chronic active hepatitis
Autoimmune haemolytic anaemia
Autoimmune Neutrogena
Autoimmune thrombocytopenic purpura
Behçet's disease
Cerebellar degeneration
Chronic active hepatitis
Chronic inflammatory demyelinating polyradiculoneuropathy
Chronic neuropathy with monoclonal gammopathy
Classic polyarteritis nodosa
Congenital adrenal hyperplasia
Cryopathies
Dermatitis herpetiformis
Diabetes
Eaton-Lambert myasthenic syndrome
Encephalomyelitis
Epidermolysis bullosa acquisita
Erythema nodosa
Gluten-sensitive enteropathy
Goodpasture's syndrome
Guillain-Barre syndrome
Hashimoto's thyroiditis
Hyperthyroidism
Idiopathic hemachromatosis
Idiopathic membranous glomerulonephritis
Isolated vasculitis of the central nervous system
Kawasaki's disease
Minimal change renal disease
Miscellaneous vasculitides
Mixed connective tissue disease
Multifocal motor neuropathy with conduction block
Multiple sclerosis
Myasthenia gravis
Opsoclonus-myoclonus syndrome
Pemphigoid
Pemphigus
pernicious anaemia
Polymyositis/dermatomyositis
Post-infective arthritides
Primary biliary sclerosis
Psoriasis
Reactive arthritides
Reiter's disease
Retinopathy
Rheumatoid arthritis
Sclerosing cholangitis
Sjögren's syndrome
Stiff-man syndrome
Subacute thyroiditis
Systemic lupus erythematosis
Systemic necrotizing vasculitides
Systemic sclerosis (scleroderma)
Takayasu's arteritis
Temporal arteritis
Thromboangiitis obliterans
Type I and type II autoimmune polyglandular syndrome
Ulcerative colitis
Uveitis
Wegener's granulomatosis
[0020] As used herein, the term "ester" refers to a group of the form -COOR, wherein R is
a radical notionally derived from the alcohol ROH. Examples of ester groups include
the physiologically hydrolysable esters such as the methyl, ethyl, n- and iso-propyl,
n-, sec- and tert-butyl, and benzyl esters.
[0021] As used herein the term "alkylene" refers to a straight or branched alkyl chain having
two unsatisfied valencies, for example -CH
2-, -CH
2CH
2-, -CH
2CH
2CH
2-, -CH(CH
3)CH
2-, -CH(CH
2CH
3)CH
2CH
2CH
2-, and -C(CH
3)
3.
[0022] As used herein the term "alkenylene" refers to a straight or branched alkenyl chain
having two unsatisfied valencies, for example-CH=CH-, -CH
2CH=CH-, -C(CH
3)=CH-, and -CH(CH
2CH
3)CH=CHCH
2-.
[0023] As used herein the term "alkynylene" refers to a straight or branched alkynyl chain
having two unsatisfied valencies, for example-C≡C-, -CH
2C≡C-, and -CH(CH
2CH
3)C≡CCH
2-.
[0024] Unless otherwise specified in the context in which it occurs, the term "substituted"
as applied to any moiety herein means substituted with at least one substituent, for
example selected from (C
1-C
6)alkyl, trifluoromethyl, (C
1-C
6)alkoxy (including the special case where a ring is substituted on adjacent ring C
atoms by alkylenedioxy such as methylenedioxy or ethylenedioxy), trifluoromethoxy,
(C
1-C
6)alkylthio, phenyl, benzyl, phenoxy, benzyloxy, hydroxy, mercapto, amino, fluoro,
chloro, bromo, cyano, nitro, oxo, -COOH, -SO
2OH, -CONH
2, -SO
2NH
2, -COR
A, -COOR
A, -SO
2OR
A, -NHCOR
A, -NHSO
2R
A, -CONHR
A, -SO
2NHR
A, -NHR
A, -NR
AR
B, -CONR
AR
B or -SO
2NR
AR
B wherein R
A and R
B are independently a (C
1-C
6)alkyl or C
2 - C
6 alkoxy group or a monocyclic carbocyclic or heterocyclic group of from 5-7 ring members,
or R
A and R
B form a ring when taken together with the nitrogen to which they are attached. In
the case where "substituted" means substituted by phenyl, benzyl, phenoxy, or benzyloxy,
the phenyl ring thereof may itself be substituted with any of the foregoing, except
phenyl, benzyl, phenoxy, or benzyloxy.
[0025] As used herein the term "aryl" refers to a mono-, bi- or tri-cyclic carbocyclic aromatic
radical, and to two such radicals covalently linked to each other, Illustrative of
such radicals are phenyl, biphenyl and napthyl.
[0026] As used herein the unqualified term "carbocyclyl" or "carbocyclic" includes aryl,
cycloalkyl and cycloalkenyl and refers to a ring system (monocyclic, bicyclic, tricyclic
or bridged) whose ring atoms are all carbon.
[0027] As used herein the unqualified term "cycloalkyl" refers to a carbocyclic ring system
which contains only single bonds between ring carbons.
[0028] As used herein the unqualified term "cycloalkenyl" refers to a carbocyclic ring system
which contains at least one double bond between a pair of ring carbons.
[0029] As used herein the term "heteroaryl" refers to a mono-, bi- or tri-cyclic aromatic
radical containing one or more heteroatoms selected from S, N and O. Illustrative
of such radicals are thienyl, benzthienyl, furyl, benzfuryl, pyrrolyl, imidazolyl,
benzimidazolyl, thiazolyl, benzthiazolyl, isothiazolyl, benzisothiazolyl, pyrazolyl,
oxazolyl, benzoxazolyl, isoxazolyl, benzisoxazolyl, isothiazolyl, triazolyl, benztriazolyl,
thiadiazolyl, oxadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl,
indolyl and indazolyl.
[0030] As used herein the unqualified term "heterocyclyl" or "heterocyclic" includes "heteroaryl"
as defined above, and in particular means a mono-, bi- or tri-cyclic or bridged non-aromatic
radical containing one or more heteroatoms selected from S, N and O and to groups
consisting of a monocyclic non-aromatic radical containing one or more such heteroatoms
which is covalently linked to another such radical or to a monocyclic carbocyclic
radical. Illustrative of such radicals are pyrrolyl, furanyl, thienyl, piperidinyl,
imidazolyl, oxazolyl, isoxazolyl, thiazolyl, thiadiazolyl, pyrazolyl, pyridinyl, pyrrolidinyl,
pyrimidinyl, morpholinyl, piperazinyl, indolyl, morpholinyl, benzfuranyl, pyranyl,
isoxazolyl, benzimidazolyl, methylenedioxyphenyl, ethylenedioxyphenyl, maleimido and
succinimido groups.
[0031] Some compounds of the invention contain one or more chiral centres because of the
presence of asymmetric carbon atoms. The presence of asymmetric carbon atoms gives
rise to stereoisomers or diastereoisomers with R or S stereochemistry at each chiral
centre. The invention includes all such stereoisomers and diastereoisomers and mixtures
thereof.
[0032] Salts of salt forming compounds of the invention include physiologically acceptable
acid addition salts for example hydrochlorides, hydrobromides, sulphates, methane
sulphonates, p-toluenesulphonates, phosphates, acetates, citrates, succinates, lactates,
tartrates, fumarates and maleates; and base addition salts, for example sodium, potassium,
magnesium, and calcium salts.
Methods
[0033] Compounds of formula (IA) described herein wherein R
1 is hydrogen and wherein R
4 represents an amide group
-C(=O)NR
6R
7 may be prepared by reaction of the appropriate amine HNR
6R
7 with a compound of formula (II) to amidate the carboxylic acid group:

the symbols Ar, R
3, X, R
6 and R
7 being as defined in relation to formula (I) above.
[0034] Compounds (II) (ie compounds (IA) described herein wherein R
1 is hydrogen and R
4 is a carboxylic acid group) may be prepared by reaction of a compound of formula
(III) with a hydrazine of formula (IV):

[0035] This reaction may result in the preparation of a mixture of the position isomers
(IIA) and (IIB):

from which the desired isomer (IIA) may be separated.
[0036] Compounds (IA) wherein R
1 is hydrogen and R
4 is an amide (-C(=O)NR
6R
7) or ester group may also be prepared from intermediate (III) by reaction with the
appropriate hydrazine (IVA)

wherein R
4 is the amide or ester group. Again the reaction may result in a mixture of the ester
analogues of the carboxylic acids (IIA) and (IIB), from which the desired ester isomer
(I) may be separated. Alternatively, the carboxylic acid compound (II) may simply
be esterified, or amidated (the latter being a route referred to above).
[0037] Compounds (IA) wherein R
1 is hydrogen and R
4 is a "reverse amide" group - NR
7C(=O)R
6 may be prepared by Curtius rearrangement (see
Ninomiya, K.; Shioiri, T.; Yamada, S. Tetrahedron (1974), 30(14), 2151-7) of the carboxylic acid (II) to the isocyanate (V)

followed by hydrolysis of the isocyanate group to an amino group and acylation of
the amino group with, for example, the acid chloride Cl-C(=O)R
6. In cases where R
7 is not hydrogen, the R
7 substituent may be introduced after the isocyanate reduction step or after the acylation
step.
[0038] Compounds (IA) wherein R
1 is hydrogen and R
4 is a urea group - NHC(=O)NHR
6 or thiourea group -NHC(=S)NHR
6 may also be prepared from the isocyanate (V) or the corresponding isothiocyanate
by reaction with the appropriate amine H
2NR
6.
[0039] Compounds (I) wherein R
4 is a carbamate group -NR
7C(=O)OR
6 may be prepared by the reaction of the isocyanate with an appropriate alcohol R
6OH.
[0040] Compounds (IA) and (IB) wherein R
1 and R
2 are C
1-C
6 alkyl may be prepared by alkylation of the corresponding compound (IA) wherein R
1 is hydrogen.
[0041] Further details of the synthetic methods for the preparation of compounds (I) as
herein described , and intermediates such as (III), may be found in the examples herein.
[0042] In the compounds herein described:
R1 and R2 independently represent hydrogen or C1-C6 alkyl, such as methyl, ethyl, n- or iso-propyl, n-, sec- or tert-butyl.
R4 represents a carboxylic acid group (-COOH) or an ester thereof, or -C(=O)NR6R7, -NR7C(=O)R6, -NR7C(=O)OR6 or -NHC(=O)NHR6, all as defined above.
When R4 is an ester group, examples include those of formula -COOR wherein R is methyl, ethyl
n- or iso-propyl, n-, sec- or tert-butyl, or benzyl ester.
R6, when present, represents H, or a radical of formula -(Alk)m-Q wherein m, Alk and Q being as defined above. When m is 1, Alk may be, for example
a straight or branched C1-C6 alkylene radical, such as -CH2-, -CH2CH2-, -CH2CH2CH2-, and -CH2CH(CH3)CH2-. Alk may also be, for example, a divalent cyclopropylene, cyclopentylene or cyclohexylene
radical. The radical Alk may be optionally substituted by, for example, OH, oxo, CF3, methoxy or ethoxy. The radical Alk may optionally contain a hetero atom, for example
in the form of an ether, thioether or amino linkage.
The group Q may represent, for example, hydrogen; -NR8R8 wherein each R8 may be the same or different and selected from hydrogen, methyl, ethyl, n- or isopropyl
or tert-butyl; an ester group for example a methyl, ethyl or benzyl ester, or an optionally
substituted aryl, aryloxy, cycloalkyl, cycloalkenyl or heterocyclic group, for example
phenyl, phenoxy, cyclopentyl, cyclohexyl, furyl, thienyl, piperidyl, or piperazinyl
group.
R7 when present represents H or C1-C6 alkyl, for example methyl, ethyl n- or iso-propyl, n-, sec- or tert-butyl; or when
taken together with the atom or atoms to which they are attached R6 and R7 form a monocyclic heterocyclic ring having 5, 6 or 7 ring atoms;
[0043] Ar may be, for example, optionally substituted phenyl, 2-, 3-, or 4-pyridyl, 2-,
or 3-furyl, 2-, or 3-thienyl, benzfur-2-yl, or benzthien-2-yl. Optional substituents
in Ar include, for example F, Cl, methyl, methoxy, or methylenedioxy. Currently it
is suitable that Ar is 3-fluorophenyl and 2-, or 3-furyl,
[0044] R
3 may be, for example, H, F, Cl, methyl, methoxy, or methylenedioxy. Currently R
3 being is very suitable.
[0045] X may be, for example a bond, or a -CH
2- or -CH
2CH
2- radical. A bond is presently suitable.
[0046] According to the present invention there is provided a compound of formula (IC) or
a pharmaceutically or veterinarily acceptable salt, hydrate or solvate thereof:

wherein
Ar represents an optionally substituted monocyclic or bicyclic aromatic or heteroaromatic
group having from 5 to 10 ring atoms,
R
6 represents a radical of formula -Alk-Q wherein
Alk is an optionally substituted divalent straight or branched C
1-C
12 alkylene, or C
2-C
12 alkenylene, or C
2-C
l2 alkynylene radical or a divalent C
3-C
12 carbocyclic radical, any of which radicals may be interrupted by one or more -O-,
-S- or -N(R
8)- radicals wherein R
8 represents H or C
1-C
4 alkyl, C
3-C
4 alkenyl, C
3-C
4 alkynyl, or C
3-C
6 cycloalkyl, and
Q represents -NR
8R
8 wherein each R
8 may be the same or different, or form a ring when taken together with the nitrogen
to which they are attached; and
R
7 represents H or C
1-C
6 alkyl; or when taken together with the atom or atoms to which they are attached R
6 and R
7 form a monocyclic heterocyclic ring having 5, 6 or 7 ring atoms.
[0047] In one embodiment of the invention there is provided a compound of the invention
wherein Alk is -CH
2-, -CH
2CH
2-, -CH
2CH
2CH
2-, or -CH
2CH(CH
3)CH
2-, or a divalent cyclopropylene, cyclopentylene or cyclohexylene radical, optionally
substituted by OH, oxo, CF
3, methoxy or ethoxy, and Q represents -NR
8R
8 wherein each R
8 may be the same or different and selected from hydrogen, methyl, ethyl, n- or isopropyl
or tert-butyl.
[0048] Preferred is a compound of the invention wherein R
7 represents hydrogen, methyl, ethyl, n- or iso-propyl, n-, sec- or tert-butyl; or
when taken together with the atom or atoms to which they are attached R
6 and R
7 form a monocyclic heterocyclic ring having 5, 6 or 7 ring atoms.
[0049] A further embodiment of the invention is a compound wherein Ar is optionally substituted
phenyl, 2-, 3-, or 4-pyridyl, 2-, or 3-furyl, 2-, or 3-thienyl, benzfur-2-yl, or benzthien-2-yl.
[0050] Another embodiment of the invention is a compound of the invention wherein Ar is
substituted by F, Cl, methyl, methoxy, or methylenedioxy.
[0051] Further preferred is a compound of the invention wherein Ar is 3-fluorophenyl, or
2- or 3-furyl.
[0052] Specific compounds of the invention are mentioned in the Examples herein.
[0053] As mentioned above, the invention contemplates pharmaceutical or veterinary composition
comprising a compound of formula (I) or a pharmaceutically or veterinarily acceptable
salt thereof together with a pharmaceutically or veterinarily acceptable excipient
or carrier. In such compositions, it will be understood that the specific dose level
for any particular patient will depend upon a variety of factors including the activity
of the specific compound employed, the age, body weight, general health, sex, diet,
time of administration, route of administration, rate of excretion, drug combination
and the cause and severity of the particular disease undergoing therapy. Optimum dose
levels and frequency of dosing will be determined by clinical trial.
[0054] The compounds with which the invention is concerned may be prepared for administration
by any route consistent with their pharmacokinetic properties. The orally administrable
compositions may be in the form of tablets, capsules, powders, granules, lozenges,
liquid or gel preparations, such as oral, topical, or sterile parenteral solutions
or suspensions. Tablets and capsules for oral administration may be in unit dose presentation
form, and may contain conventional excipients such as binding agents, for example
syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinyl-pyrrolidone; fillers for
example lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine; tabletting
lubricant, for example magnesium stearate, talc, polyethylene glycol or silica; disintegrants
for example potato starch, or acceptable wetting agents such as sodium lauryl sulphate.
The tablets may be coated according to methods well known in normal pharmaceutical
practice. Oral liquid preparations may be in the form of, for example, aqueous or
oily suspensions, solutions, emulsions, syrups or elixirs, or may be presented as
a dry product for reconstitution with water or other suitable vehicle before use.
Such liquid preparations may contain conventional additives such as suspending agents,
for example sorbitol, syrup, methyl cellulose, glucose syrup, gelatin hydrogenated
edible fats; emulsifying agents, for example lecithin, sorbitan monooleate, or acacia;
non-aqueous vehicles (which may include edible oils), for example almond oil, fractionated
coconut oil, oily esters such as glycerine, propylene glycol, or ethyl alcohol; preservatives,
for example methyl or propyl p-hydroxybenzoate or sorbic acid, and if desired conventional
flavouring or colouring agents.
[0055] For topical application to the skin, the drug may be made up into a cream, lotion
or ointment. Cream or ointment formulations which may be used for the drug are conventional
formulations well known in the art, for example as described in standard textbooks
of pharmaceutics such as the British Pharmacopoeia.
[0056] For topical application to the eye, the drug may be made up into a solution or suspension
in a suitable sterile aqueous or non aqueous vehicle. Additives, for instance buffers
such as sodium metabisulphite or disodium edeate; preservatives including bactericidal
and fungicidal agents such as phenyl mercuric acetate or nitrate, benzalkonium chloride
or chlorhexidine, and thickening agents such as hypromellose may also be included.
[0057] The active ingredient may also be administered parenterally in a sterile medium.
Depending on the vehicle and concentration used, the drug can either be suspended
or dissolved in the vehicle. Advantageously, adjuvants such as a local anaesthetic,
preservative and buffering agents can be dissolved in the vehicle.
[0058] Accordingly, another embodiment of the invention is a pharmaceutical or veterinary
composition comprising a compound of the invention together with a pharmaceutically
or veterinarily acceptable excipient or carrier.
[0059] Embodiments of the invention are described in the following non-limiting Examples:
[0060] The following abbreviations are used in the experimental descriptions:
- DMF
- Dimethyl formamide
- DMA
- Dimethyl acetamide
- DMSO
- Dimethyl sulphoxide
- THF
- Tetrahydrofuran
- HBTU
- O-Benzotriazol-1-yl-N,N,N',N'-tetramethyluronium hexafluorophosphate
- HPLC
- High performance liquid chromatography
- LCMS
- Liquid chromatography mass spectrum
- NMR
- Nuclear magnetic resonance spectroscopy
Example 1
4-(5-Oxo-3-pyrazin-2-yl-2,5-dihydro-pyrazol-1-yl)-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
[0061]

Step 1: Preparation of 4-(N'-tert-Butoxycarbonyl-hydrazino)-benzoic acid
[0062]

[0063] To a deep red solution of p-hydrazinobenzoic acid (32.86 mmol, 5.00 g) in 2M NaOH
(100 ml) and THF (70 ml) was added di-tertbutyl dicarbonate (2.0 eq, 65.72 mmol, 14.34
g). This was stirred at rt over a weekend. Another aliquot of di-tertbutyl dicarbonate
(3.5 g) was added to the reaction mixture, and this stirred at room temp for a further
24 hours. A further 0.5 eq p-hydrazinobenzoic acid added to the reaction mixture.
This was then stirred for a further 24 hours. 10% citric acid solution was added until
a pH of 4 was obtained. The product was then extracted with ethyl acetate, the organics
washed with brine, and then dried over Na
2SO
4. Concentration
in vacuo afforded a pale yellow oil, containing residual tert-BuOH. Hexane was added to the
mixture. Precipitation was observed and the solids were collected by filtration, washed
with hexane and dried under vacuum at 35°C. An orange powder was obtained (8.40 g).
Step 2: Preparation of N'-[4-(1,2,2,6,6-Pentamethyl-piperidin-4-ylcarbamoyl)-phenyl]-hydrazinecarboxylic
acid tert-butyl ester
[0064]

[0065] To a solution of 4-(N'-tert-Butoxycarbonyl-hydrazino)-benzoic acid (4.452g) in DMA
(30ml) was added disopropyl ethyl amine (6.16ml) and HBTU (6.69g) with stirring at
room temp. 4-Amino-1,2,2,6,6-pentamethylpiperidine (3g) was then added to the stirred
solution. Stirring continued at room temp for 4hrs. The solution was partitioned between
ethyl acetate (6 X 20 ml) and water. The organic fraction was taken, washed with brine,
dried over MgSO
4 and the solvent removed under vacuum. This revealed a deep orange oil (6.2g, 86%).
Step 3: Preparation of 4-Hydrazino-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
[0066]

[0067] N'-[4-(1,2,2,6,6-Pentamethyl-piperidin-4-ylcarbamoyl)-phenyl]-hydrazinecarboxylic
acid tert-butyl ester was dissolved in 4M HCl in dioxane (30ml) and left to stir for
1-2hrs. The solution went quickly from a deep orange colour to a bright orange colour.
After 1 hr reaction time, the solvent was removed under vacuum to reveal an orange
oil that under a vacuum for several minutes crystalised out to give orange crystals
in a sticky orange oil. Yield: 4.68 g, 87%.
Step 4: Preparation of 3-Oxo-3-pyrazin-2-yl-propionic acid, ethyl ester.
[0068]

[0069] To a stirred solution of diethyl malonate (1.25 ml, 1.32g) in THF (20 ml) under an
atmosphere of nitrogen at -60°C was added nbutyl lithium (2.5 M, 9 ml) dropwise over
15 min, keeping the temperature constant. The reaction became a cloudy white colour
from the formation of the di-lithium salt then became yellowish. After 10 min, the
reaction was cooled to -78°C, when a solution of pyrazine-2-carbonyl chloride (0.5
g, dark purple solution in THF (10 ml)) was added dropwise over 15 min. The reaction
then warmed to -45°C and stirred for 1 h. The reaction was then poured into 1 M HCl
solution (35 ml) with stirring. This was transferred to a separating funnel, and extracted
with CH
2Cl
2 (2 x 150 ml). The combined organic layers were then washed with sat. NaCO
3 soln (1 x 30 ml) and then dried over MgSO
4, filtered and concentrated
in vacuo to give the product as a brown oil. Yield 0.65g, 45%.
Step 5: Preparation of 4-(5-Oxo-3-pyrazin-2-yl-2,5-dihydro-pyrazol-1-yl)-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
[0070]

[0071] 3-Oxo-3-pyrazin-2-yl-propionic acid, ethyl ester (78 mg) and 4-hydrazino-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
(141mg) were dissolved in ethanol (3.5 ml) and acetic acid (0.5 ml) and the solution
stirred at 65 °C for 2h. Concentration
in vacuo and purification by HPLC gave the expected product. LC/MS: main peak is product (m/z:
434)
Example 2
4-(3-Isoxazol-5-yl-5-oxo-2,5-dihydro-pyrazol-1-yl)-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
[0072]

Step 1: Preparation of 3-lsoxazol-5-yl-3-oxo-propionic acid ethyl ester
[0073]

[0074] To a stirred solution of diethyl malonate (2.6 ml, 2.74g) in THF (40 ml) under an
atmosphere of nitrogen at -60°C was added nbutyl lithium (2.5 M, 18.9 ml) dropwise
over 15 mins, keeping the temperature constant. The reaction became a cloudy white
colour from the formation of the di-lithium salt then became yellowish. After 10 mins,
the reaction was cooled to -78°C, when a solution of Isoxazole-5-carbonyl chloride
(1 g) in THF (10 ml) was added dropwise over 15 mins. The reaction then warmed to
-45°C and stirred for 1 h, the solution had gone pale brown. The reaction was then
poured into 1 M HCl solution (50 ml) with stirring and extracted with CH
2Cl
2 (2 x 150 ml). The combined organic layers were washed with sat. NaCO
3 soln (1 x 30 ml), dried over MgSO
4, filtered and concentrated
in vacuo to give the product as a pale oil which was used as such in the next step. Yield
1.1g, 35.1%.
Step 2: Preparation of 4-(3-Isoxazol-5-yl-5-oxo-2,5-dihydro-pyrazol-1-yl)-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
[0075]

[0076] 3-lsoxazol-5-yl-3-oxo-propionic acid ethyl ester (49 mg) and 4-Hydrazino-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
(93 mg) were dissolved into ethanol (2.5 ml) and acetic acid (0.3 ml) and the solution
stirred at 65 °C for 2h. Concentration
in vacuo and purification by HPLC gave the expected product. LC/MS: main peak is product (m/z:
424.3)
[0077] The compound of Example 2 had activity rating * in the HTRF assay described below.
Example 3
4-(3-Furan-2-yl-4-methyl-5-oxo-2,5-dihydro-pyrazol-1-yl)-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
[0078]

Step 1: Preparation of 3-furan-2-yl-2-methyl-3-oxo-propionic acid ethyl ester
[0079]

[0080] In a flask were placed ethyl 3-(2-furyl)-3-oxopropanoate (0.5g), iodomethane (0.14
ml), finely ground potassium carbonate (0.75g) and acetone (5 ml). The mixture was
stirred at reflux for 2h. A further portion of iodomethane (0.9mmol, 0.056 ml) and
potassium carbonate (0.9 mmol, 0.12g) were added and the mixture stirred at reflux
for 1 h. The reaction mixture was filtered and concentrated under vacuum. Yield (0.5g,
93%).
Preparation of 4-(3-Furan-2-yl-4-methyl-5-oxo-2,5-dihydro-pyrazol-1-yl)-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
[0081]

[0082] 3-furan-2-yl-2-methyl-3-oxo-propionic acid ethyl ester (49 mg) and 4-Hydrazino-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
(85 mg) in 0.5 ml of acetic acid were heated up at 65 °C for 2h. Concentration
in vacuo and purification by HPLC gave the expected product. MH+ = 437.3
[0083] The compound of Example 3 had activity rating * in the HTRF assay described below.
Example 4
4-(3-Furan-2-yl-4,4-dimethyl-5-oxo-4,5-dihydro-pyrazol-1-yl)-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
[0084]

Step 1: Preparation of 3-Furan-2-yl-2,2-dimethyl-3-oxo-propionic acid ethyl ester
[0085]

[0086] 3-furan-2-yl-2-methyl-3-oxo-propionic acid ethyl ester (49 mg) was added sodium ethoxide
(0.22 ml) and 0.5 ml ethanol. A solid precipitates. The solution was stirred at room
temperature for 1h, iodomethane was added and the suspension stirred at room temperature
for 3 h. Concentration
in vacuo and purification by HPLC gave the expected product.
Step 2: Preparation of 4-(3-Furan-2-yl-4,4-dimethyl-5-oxo-4,5-dihydro-pyrazol-1-yl)-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
[0087]

[0088] 3-Furan-2-yl-2,2-dimethyl-3-oxo-propionic acid ethyl ester (53 mg) and 4-Hydrazino-N-(1,2,2,6,6-pentamethyl-piperidin-4-yl)-benzamide
(85 mg) in 0.5 ml of acetic acid were heated up at 65 °C for 2h. Concentration
in vacuo and purification by HPLC gave the expected product (MH+: 451.4)
Additional Examples
Assay Protocols
The use of BIAcore biomolecular interaction analysis
[0090] Biotinylated human CD80 (hCD80-BT) is a recombinant soluble form of a membrane bound
receptor molecule (CD80) which binds to CD28 to initiate T cell activation. The interaction
between CD80 and CD28 has been extensively investigated (Collins et al, 2002). Biotinlyated
human HLA-A2-tax is the recombinant soluble form of a membrane bound receptor molecule
that has been used in this example as a control protein, and is not expected to interact
with the compounds.
[0091] The BlAcore S51™ system was used for screening the compounds of Examples 1-4 above.
A series S sensor chip CM5 was docked onto the BlAcore S51™. Streptavidin was coupled
to the carboxymethyl surface using standard amine coupling. The chip surface was activated
with 0.2M EDC / 0.05M NHS, followed by binding of streptavidin (0.25 mg/ml in 10 mM
sodium acetate pH 5.0) and saturation of unoccupied sites with 1 M ethylenediamine.
[0092] The BlAcore S51 sensor chip has two separate sensor spots for immobilisation of proteins.
hCD80-BT was immobilised on the streptavidin-coated surface of one sensor spot until
a response of approximately 3000 RU was observed. A protein to control for non-specific
binding of the compound was immobilised on a second sensor spot. The control protein
used for these experiments was a biotinylated, soluble form of the human HLA protein.
[0093] Dilution series of compounds (1000nM - 0.05nM) were prepared in running buffer (10
mM, pH 7.4, 150 mM NaCl, 0.005% P20; 5% DMSO).
[0094] BlAcore S51™ was run at a flow rate of 30 µl/min using running buffer. Compounds
and DMSO standard solutions for correction of data for solvent effects were injected.
Data were recorded automatically and were analysed using BlAcore S51 Evaluation software.
[0095] The interaction between CD80 and the endogenous protein ligand (CD28) is highly specific,
but relatively weak, with a K
D of 4750 nM, and an off-rate of greater than 0.2 s
-1 . The compounds of Examples 7, 11 & 18-21 have greater affinity and longer residence
times on CD80 than CD28, having K
Ds of less than 100nM, and off-rates of 2x10
-2, indicating that the pyrazolones will be able to compete effectively with the endogenous
ligand. The pyrazolones showed no detectable interaction with the control protein.
References
Inhibition of production of interleukin-2 (IL-2) by human Jurkat T cells. Method
[0097] Human Raji cells were dispensed at a concentration of 2x10
5 cells per well in RPMI-1640 medium supplemented with 10% fetal calf serum, 1% penicillin/streptomycin,
1% glutamine (RPMI medium) in a 96-well round bottom microtitre plate. Compounds under
investigation (dissolved in 100% DMSO) were diluted to eight-fold the desired final
concentration in RPMI medium and added to the required final concentration for a total
volume of 200µl per well. After 20 minutes incubation at 37°C, Jurkat T cells were
added at a concentration of 2x10
5 cells per well. Monoclonal antibody to CD3 (UCHT1, R&D Systems) was added to the
cultures at a final concentration of 1µg per ml, and where indicated, monoclonal antibody
to CD28 (CD28.2, BD-Pharmingen) was also added at a concentration of 2.5µg per ml.
Cells were cultured at 37°C for 5 hours, after which the plates were centrifuged and
the supernatants harvested for IL-2 ELISA assay using the IL-2 Eli-pair kit (DIACLONE
Research, Besancon, France) according to the manufacturers instructions.
[0098] By way of example, the compound of Example 26 gave 52% inhibition at 30 µM.
Homogenous Time Resolved Fluorescence Assay
[0099] The examples described above were tested in a cell free Homogenous Time Resolved
Fluorescence (HTRF) assay to determine their activity as inhibitors of the CD80-CD28
interaction.
[0100] In the assay, europium and allophycocyanin (APC) are associated with CD28 and CD80
indirectly (through antibody linkers) to form a complex, which brings the europium
and APC into close proximity to generate a signal. The complex comprises the following
six proteins: fluorescent label 1, linker antibody 1, CD28 fusion protein, CD80 fusion
protein, linker antibody 2, and fluorescent label 2. The table below describes these
reagents in greater detail.
| Fluorescent label 1 |
Anti-Rabbit IgG labelled with Europium (1µg/ml) |
| Linker antibody 1 |
Rabbit IgG specific for mouse Fc fragment (3µg/ml) |
| CD28 fusion protein |
CD28 - mouse Fc fragment fusion protein (0.48µg/ml) |
| CD80 fusion protein |
CD80 mouse Fab fragment (C215) fusion protein (1.9/µg/ml) |
| Linker antibody 2 |
GαMK-biotin: biotinylated goat IgG specific for mouse kappa chain (2µg/ml) |
| Fluorescent label 2 |
SA-APC: streptavidin labelled allophycocyanin (8µg/ml) |
[0101] On formation of the complex, europium and APC are brought into proximity and a signal
is generated.
[0102] Non-specific interaction was measured by substituting a mouse Fab fragment (C215)
for the CD80 mouse Fab fragment fusion protein (1.9µg/ml). The assay was carried out
in black 384 well plates in a final volume of 30µl. Assay buffer: 50mM Tris-HCl, 150mM
NaCl pH7.8, containing 0.1 % BSA (w/v) added just prior to use.
[0103] Compounds were added to the above reagents in a concentration series ranging between
100µM - 1.7nM. The reaction was incubated for 4 hours at room temperature. Dual measurements
were made using a Wallac Victor 1420 Multilabel Counter. First measurement: excitation
340nm, emission 665nm, delay 50µs, window time 200µs. second measurement: excitation
340nm, emission 615nm, delay 50µs, window time 200µs. Counts were automatically corrected
for fluorescence crossover, quenching and background. The EC50 activities of compounds
tested are recorded as: EC50: * = >10 µM, ** = 1-10 µM, *** = <1 µM.